On a couple of occasions recently, when applying carb heat shortly after startup (during power checks), engine RPM has increased. This is a standard C172, except for a modifed "tuned" exhaust system. If I wait a minute or so, then do the checks again, normal behaviour is resumed, and the drop in RPM is again normal.
Anyone have any ideas why the application of "warm" air (not that it would be very warm just after startup) - with mixture full rich - would cause a power increase ?
Cheers,
FF
